import java.util.Scanner;

public class Main {
    public static int fib(int n) {
        if(n==1)return 0;
        else if(n==2)return 1;
        int a=0,b=1;
        for (int i = 3; i <=n; i++) {
            int temp=a+b;
            a=b;
            b=temp;
        }
        return b;
    }
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int ret=fib(n);

            System.out.println("第"+n+"项是"+ret);
    }
}


